The principal objective of this work is the synthesis of new high molecular weight polymers that can be used in biomedical applications, and particularly in cardiovascular applications. The polymers to be synthesized are new polyphosphazenes. They contain alternating phosphorus and nitrogen atoms in the skeleton with two substituent groups attached to each phosphorus, (N equals PR2)n. Special emphasis will be placed on the synthesis of polymers which contain amino acid ester side groups both alone and together with simple amino residues, such as methylamino groups. Additional polymers will be investigated that contain heparin residues attached to the chain and cyclic organic compounds, such as procaine, purine, etc. The principal roadblock to be overcome is to identify the chain degradation reaction that takes place when carbonyl-containing substituents are introduced, and to block that reaction mechanism. The polymers are expected to be biocompatible with human body tissues and to be strong candidates for use in the artificial heart program. Some are expected to form valuable carrier molecules for therapeutic drugs, birth control agents, or anesthetic molecules. Research on this project does not include human subjects.